• Mel Gorman's avatar
    mm: throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is... · 5515061d
    Mel Gorman authored
    mm: throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage
    
    If swap is backed by network storage such as NBD, there is a risk that a
    large number of reclaimers can hang the system by consuming all
    PF_MEMALLOC reserves.  To avoid these hangs, the administrator must tune
    min_free_kbytes in advance which is a bit fragile.
    
    This patch throttles direct reclaimers if half the PF_MEMALLOC reserves
    are in use.  If the system is routinely getting throttled the system
    administrator can increase min_free_kbytes so degradation is smoother but
    the system will keep running.
    Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
    Cc: David Miller <davem@davemloft.net>
    Cc: Neil Brown <neilb@suse.de>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Mike Christie <michaelc@cs.wisc.edu>
    Cc: Eric B Munson <emunson@mgebm.net>
    Cc: Eric Dumazet <eric.dumazet@gmail.com>
    Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
    Cc: Mel Gorman <mgorman@suse.de>
    Cc: Christoph Lameter <cl@linux.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    5515061d
mmzone.h 38 KB